Joint arthroplasty is a well known surgical procedure by which a diseased and/or damaged natural joint is replaced by a prosthetic joint. Joint arthroplasty is commonly performed for hips, knees, elbows, and other joints. The health and condition of the joint to be replaced dictate the type of prosthesis necessary to replace the natural joint. For example, in a total hip arthroplasty an acetabular cup may be implanted in the pelvis to replace the natural acetabulum. In many instances, it is also necessary to replace the head of the femur with a prosthetic femoral head.
Surgical success and long term patient comfort depend to a large extent on the proper alignment of the prosthetic joint components as well as the interaction between the wear surfaces of the acetabular cup and the femoral head. High strength materials with good wear properties and low coefficient of friction offer the most promise for long term joint replacement solutions.
Currently, the wear surfaces of joint prostheses are made from a variety of materials. Among the most prevalent are metals and metal alloys, polymers, and ceramics. Ceramic on metal and ceramic on ceramic wear surfaces are currently common. One challenge facing designers of joint prostheses such as hip prostheses is that the properties that contribute to the proper integration of an acetabular cup, for example, into bone include relatively high porosity of the surface that will be embedded in bone. However, the wear surface should be a smooth, strong surface with a low coefficent of friction.
There is thus a need for joint prostheses and methods of making joint prostheses that are able to exhibit different properties for different portions of the prosthesis.